PHILADELPHIA (CBS) — A large winter storm was making its way through the Delaware Valley Sunday causing travel nightmares.

The snow began falling heavier than expected, and the National Weather Service placed Philadelphia and extreme southeastern Pennsylvania under a winter storm warning, saying the region could get 3 to 6 inches of snow before changing to sleet and rain later Sunday night into early Monday morning.

Roadways quickly became very hazardous and officials were urging drivers to use extreme caution.

Police were reporting multiple accidents along some major roads in the area, including I-95, I-476 and the Pennsylvania Turnpike, with some crashes blocking traffic entirely.

The Turnpike was closed much of the day Sunday westbound between Downingtown and Morgantown, but has now reopened to traffic.

The weather also forced the closure of some area bridges, including the Platt Bridge and Delaware Memorial Bridge.